Vehicle Analysis Branch Langley Research Center Study of Orbiter-like Cargo Carrier on Crew Launch Vehicle October 25, 2006 FEMCI Workshop 2006 Goddard

Vehicle Analysis Branch

Langley Research Center

Study of Orbiter-like Cargo Carrier on Crew Launch Vehicle

October 25, 2006FEMCI Workshop 2006

Goddard Space Flight Center, Greenbelt, Maryland

Zoran N. Martinovic

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Orbiter-like Cargo CarrierOn CLV

Content:

• Study objective and requirements• Vehicle size and two candidate designs• Structural requirements, loads and interfaces• Outline of analytical process• Details of two designs and analytical weight prediction• Non-optimal weight estimates• Summary

Zoran N. Martinovic/NASA LaRC/VAB October 2006

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Objective:

• Design and determine primary structures analytical weight for an Orbiter-like Cargo Carrier concept that was examined during the early phase of the Crew Launch Vehicle (CLV ) program to fly attached on top of CLV

• This vehicle is not part of the current program


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Design Requirements:

• Cargo Carrier was envisioned to enable delivery of all International Space Station (ISS) elements (15 ft dia., 48 ft length, 55,000 lb weight)in Orbiter like payload accommodation environment

• No modifications of existing payload hardware was required


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Size

• Inner diameter equaled Orbiter’s inner diameter of 15 feet (4.57 meters)

• Outer diameter was 18 feet (5.49 meters)• Length of Cargo Bay equaled the useful length of

Orbiter Payload Bay when Orbiter was configured with ISS external airlock and Orbiter Docking Structure, 598 inch or 49.8 feet (15.2 meters).


2 ft 49.8 ft 16.7 ft

18 ft Out. Dia15 ft In. Dia.


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Design

Two designs were considered and sized• Open Wall Design that consisted of stiffened skin

with stringers, longerons and frames.

• Closed Wall Design that had outer stiffened skin closed with inner skin that resists torque loads.


Open Wall Design Closed Wall Design


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Design (cont.)

Cargo Bay doors were designed and sizedand there influence factored in the ClosedWall Design sizing of Cargo Carrier



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* Space Shuttle System Payload Accommodations, NSTS 07700 Vol. XIV

Structural Requirements

• Payload attachments were like in Orbiter and statically determinate *• Load Factors: axial 4g, lateral 1g (1.41 g lateral combined).• Safety Factor (Ultimate Load/Limit Load) equal to 1.5



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Loads • Six sets of combined loads

Aero Load

Inertia Load

• Inertia loads due to acceleration: axial 4g, lateral 1g (1.41g for lateral combined).• Aero loads due to dynamic pressure of 850 psf: drag and lateral, CD=0.05, CL=0.01 (CL=0.014 for lateral combined) M>2 and Alpha = 1 deg (Bruhn – Saturn V*).

* Analysis and Design of Missile Structures, E.F. Bruhn, Tri-State Offset Co., 1967Zoran N. Martinovic/NASA LaRC/VAB October 2006


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Payload and Payload attachment • Payload weight 55,000 lb (25,000 kg)• Payload modeled as a lump mass with inertia properties of a cylinder 500 inch long and 168 inch diameter

Payload


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Carrier attachment to launch vehicle/service module

• Six ball joints at longerons (60 deg. apart)


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Vehicle Geometry and WeightsCONSIZ

I-DEAS FE Model

Mach Number

Altitude, ft. *10-3

5 10 15 20 25

3.5

3

2.5

2.

1.5

1.0

0.5

Orbiter ascent

Orbiter entry

Boosterstaging

A – Loading conditions 1 thru 6, and 14 thru 16 are on the groundB – max QC – max ascent wing normal forceD – pre stagingE – post stagingF – max ascent axial accelG –hypersonic entryH – subsonic maneuver

A

H

BCD

E

G

F

POST Flight Profile with Accelerations & CBAERO generated Aero-forces

Loaded I-DEAS FE Model

HSLoad / HYPERSIZER Model

Panel sizing in HYPERSIZER

Load BalancingEXCEL Solver

[M], [K]Finite elements organized in groups/Panels

Running loads [Nx, Ny, Nxy ……]

• Panel/beam Concept• Material• Limits on design variables• Failure Criteria

Assign:

New [K] &Struct. [M]

LOFT Generated MeshINPUTGeometry

INPUTLump Mass

INPUTGs & Fs

INPUTFE Mesh

Process Outline



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Open Wall Design

Al 2024-T3

Al 2024-T3

Al 2024-T3 face-sheetsHexcel 1/8-5052-.0015 core

Al 7075-T6

Frame spacing 59.8 inchLongeron spacing 60 deg.


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0.88 lbs/sq.ft

1.16 lbs/sq.ft

1.23 lbs/sq.ft

1.52 lbs/sq.ft

Panel concept Unit weight

Earlier study showed: Combined fixed/simply

supported aluminum panel 36 inch x 80 inch,

radius 108 inchloaded with 1000 lb/in

Ultimate Load = 1.5 Applied


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Open Wall Design (cont.)• Sizing of panels and beams done by an iterative process between UGS/I-Deas (analysis) and Collier/HyperSizer (sizing) tools.

Iteration Weight (lbs)

1 12,408

2 13,671

3 15,104

4 14,944

5 15,307

W = 15,307 lbs = 5,333 lbs (Panels) + 9,974 lbs (Beams)


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Closed Wall Design

Al 2024-T3Outer skin

Al 2024-T3


Al 7075-T6Beam Caps

Inner Skin

Beam webs

Beam Cross

Section

Sandwich

Extrusion


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Closed Wall Design (cont.)• Same process used for sizing as in Open Wall Design


1 8,643

2 7,858

3 8,062

4 8,171

W = 8,171 lbs = 6,675 lbs (Panels) + 1,496 lbs (Beam Caps)

Open Wall Weight (lbs) 15,307

Closed Wall Weight (lbs) 8,171


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Adding symmetry to the Closed Wall Design• Optimization produces an asymmetric structureabout the central vehicle plane due to asymmetric loads

Sym. Closed Wall Weight (lbs)

After 5th Iteration

10,525

Closed Wall Weight (lbs) 8,171

Unit weight (lb/sqft)Unit weight (lb/sqft)


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Cargo Bay Doors Design• The same six combined aero/inertia loads were applied as for the rest of the vehicle.• Four ball joints modeled doors attachments to the vehicle.


Al 7075-T6



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Cargo Bay Doors Design (cont.)• During the last iteration, constraint forces, caused by door loads, were computed at hingelocations and saved for further design


1 1,596

2 1,483

3 1,484

W = 1,484 lbs = 1,333 lbs (Panels) + 151 lbs (Beams)


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Closed Wall Design with Bay Doors loads• Six sets of concentrated loads on cargo bay hinges added to six load cases


1 7,882

2 7,897

Symmetry run 10,613

W = 10,613 = 8963 lbs (Panels) + 1,650 lbs (Beam Caps)

Weight no hinge loads (lbs) 10,525

Weight with hinge loads (lbs) 10,613

Total vehicle primary structure weight (with doors) = 10,613+1,484 = 12,097 lbs (5,499 kg)

Note:One out of

six loads shown


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Non Optimal Weight Estimates • 12,097 lb is weight of primary analytical structure• Assume that non optima and secondary structure

add 15% to the weight:

Total structural “as-built weight” estimate would be 13,912 lb



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Summary

• Process for rapid design and structural weight estimation was applied to Orbiter-like Cargo Carrier• Two structural design concepts were analyzedand one of them – Closed Wall Design was selected as a superior among the two• Process produced analytical structural weight of 12,097 lb • Estimated total structural weight, with non-optimalweight and secondary structure weight, was 13,912 lb


Documents

Vehicle Analysis Branch Langley Research Center Study of Orbiter-like Cargo Carrier on Crew Launch Vehicle October 25, 2006 FEMCI Workshop 2006 Goddard